The subject matter of the present invention relates generally to the manufacture of articles of folded sheet material, and in particular to machines for manufacturing sleuters or other articles of folded plasterboard. The machine of the present invention makes load spacers or sleuters from plasterboard remnants which are cut into a standard length, scored along fold lines, and transmitted into a folding apparatus which simultaneously folds and breaks the plasterboard member into two separate members having accordian-like pleats. The pleated members are then compressed and stapled to form the completed sleuters. Such sleuters are used as spacers or risers beneath stacks of sheet material, such as gypsum board, for shipping purposes or for storage. The sleuters enable the insertion of the forklifts of lift truck beneath the stack of sheet material for movement thereof and can be used as spacers between stacks sorted into different sized stacks.
Sleuters of folded gypsum boards have the advantage that they do not discolor or physically mark the surface of the plasterboard or other sheet material stacked thereon, and therefore have an advantage over conventional sleuters of wood in this regard. In addition, the machine of the present invention enables plasterboard remnants to be made into commercial articles and thereby greatly reduces waste in plants manufacturing gypsum board sheets.
It has been proposed to fold plasterboard and other sheet material by cutting or scoring it in lines on one side or both sides, as shown in U.S. Pat. No. 2,529,210 of Butler and U.S. Pat. No. 3,646,412 of Sterns et al. Heretofore, folding has been accomplished by moving upper and lower folding members or blades toward each other to provide pleats in a continuous web of sheet material, as shown in U.S. Pat. No. 2,194,344 of Wikander et al, and U.S. Pat. No. 2,670,026 of Unger. However, in these prior apparatus, the folding members or blades are fixed, not pivoted or moved laterally to compress the folds together and do not break the sheet material into two separate members, in the manner of the present invention.
Previous attempts to fold plasterboard as it was moved continuously were unsuccessful due to breakage and resulting jamb-ups. These problems have been overcome in the present invention by providing a conveyor means which moves the plasterboard intermittently between the work stations performing the operations of cutting, scoring, folding and breaking, and stapling. This intermittent movement is provided by a timer operating a clutch connected between the motor shaft and the drive shaft of the conveyor.
The amount of gypsum dust produced during the scoring operation is greatly reduced by operating saw blades providing such scoring at the same speed as the conveyor chain. The plasterboard is accurately positioned at each of the operating stations by stop surfaces on lugs attached to the conveyor chain and the same lugs also act as drive means for moving the plasterboard from one work station to another.